The present invention relates to a magnetron apparatus for use as a high-frequency generator in electric apparatuses, such as a microwave oven.
A magnetron apparatus is a microwave oscillation tube operating at a fundamental frequency of 2,450 MHz, for example. The microwave oscillation tube is used as a high-frequency generator in electric apparatuses that use microwaves, such as a microwave heater and a microwave discharge lamp. Generally, this kind of magnetron apparatus has a configuration wherein its cathode and anode are disposed coaxially and cylindrically.
FIG. 11 is a sectional view showing an internal configuration of a conventional magnetron apparatus. As shown in FIG. 11, the conventional magnetron apparatus comprises a vacuum tube portion 101 disposed at the central portion thereof, a plurality of heat radiating fins 102 disposed around the outer circumference of the vacuum tube portion 101, a pair of annular magnets 103 disposed so as to be coaxial with the vacuum tube portion 101, a pair of frame yokes 104 magnetically connected to the annular magnets 103 so as to form a magnetic circuit, and a filter circuit 105.
The vacuum tube portion 101 comprises an anode cylinder 106, a cathode 107 disposed so as to be coaxial with the anode cylinder 106, a plurality of plate-shaped anode segments 108 disposed radially around the central axis of the anode cylinder 106, two strap rings 109 and 110 for connecting these anode segments 108 alternately and electrically, and an antenna 111 for discharging microwaves, one end of which is connected to one of the anode segments 108.
As shown in FIG. 11, the strap rings 109 and 110, being large and small in diameter respectively, are connected to both the upper end face and lower end faces of the plate-shaped anode segments 108. In order that the strap rings 109 and 110 are connected to either upper or lower end face of the anode segment 108, a first recessed portion 112 is formed on one of the end faces of the anode segment 108, and a second recessed portion 113 is formed on the other end face. In addition, a groove 114 for securing the antenna 111 is formed on either one of the end faces of the anode segments 108. The anode segments 108 formed as described above are arranged so that the end faces are placed alternately. Hence, in the anode segments 108 disposed radially, the first end face of one of two anode segments adjacent to each other, wherein the first recessed portion 112 is formed, is disposed so as to face the second end face of the other anode segment, wherein the second recessed portion 113 is formed. The outer circumferential ends of the anode segments 108 disposed radially are secured to the inside wall face of the anode cylinder 106.
In recent years, in the field of electric apparatuses incorporating magnetron apparatuses, in order to pursue the development of new application apparatuses and the cultivation of new markets, compact magnetron apparatuses are desired to be developed. However, in the conventional magnetron apparatus, when the inside diameter of the anode cylinder was made smaller than its conventional value by about 35 mm in order to make the magnetron apparatus more compact, there was a problem of causing the oscillation frequency to become higher than the specified frequency. Hence, the inside diameter was unable to be made smaller simply in the configuration of the conventional magnetron apparatus. Since the anode cylinder was unable to be made smaller simply in the conventional magnetron apparatus as described above, downsizing was hampered.
The present invention is intended to solve the various problems encountered in the above-mentioned conventional apparatus and to provide a compact magnetron apparatus.
A magnetron apparatus in accordance with the present invention comprises:
a substantially cylindrical anode cylinder,
a plurality of plate-shaped anode segments which are secured to an inside wall face of the anode cylinder, and which are disposed radially around the central axis of the anode cylinder so that the main face thereof is disposed in parallel with the central axis of the anode cylinder, and
a first strap ring and a second strap ring for alternately and electrically connecting the anode segments disposed radially, wherein
the anode segment has a first end face disposed on a first-direction side in parallel with the central axis of the anode cylinder,
a second end face disposed on a second-direction side in parallel with the central axis of the anode cylinder,
a first notch formed by being cut from the first end face in substantially parallel with the central axis of the anode cylinder so that a predetermined space is arranged between the anode segment and the first strap ring,
a second notch formed by being cut from the second end face in substantially parallel with the central axis of the anode cylinder so that a predetermined space is arranged between the anode segment and the second strap ring, and
a third notch formed by being cut from the second end face in substantially parallel with the central axis of the anode cylinder at a position deviated with respect to the formation position of the first notch in the direction from the central axis of the anode cylinder to the outer circumference thereof. The magnetron apparatus configured as described above is provided with the anode segments having a special shape obtained by forming the notches therein. Hence, the magnetron apparatus can use the anode cylinder smaller in inside diameter than that of the conventional apparatus and the plate-shaped anode segments smaller in size than those of the conventional apparatus. Accordingly, in the magnetron apparatus in accordance with the present invention, the passage of high-frequency current flowing through the resonator comprising the anode segments adjacent to each other, the anode cylinder and the strap rings is formed so as to be bent, narrow and long. Therefore, even when the anode cylinder smaller in inside diameter than that of the conventional apparatus and the plate-shaped anode segments smaller in size than those of the conventional apparatus are used, the magnetron apparatus in accordance with the present invention can have an inductance similar to that of the conventional magnetron apparatus.
In the magnetron apparatus in accordance with the present invention, a groove for securing a microwave discharging antenna may be formed in the first end face of the anode segment at a position different from the formation position of the first notch.
In the magnetron apparatus in accordance with the present invention, the depth of the first notch may be larger than the distance between the bottom of the first notch and the second end face.
In the magnetron apparatus in accordance with the present invention, the depth of the third notch may be larger than the distance between the bottom of the third notch and the first end face.
In the magnetron apparatus in accordance with the present invention, the depth of the first notch may be different from the depth of the third notch.
In the magnetron apparatus in accordance with the present invention, the depth of the first notch may be substantially identical to the depth of the third notch.
In the magnetron apparatus in accordance with the present invention, the first notch and the third notch may have rectangular shapes.
In the magnetron apparatus in accordance with the present invention, the first notch and the third notch may have curved shapes.
In the magnetron apparatus in accordance with the present invention, the first notch and the third notch may be formed so as to have sides inclined with respect to the central axis of the anode cylinder.
In the magnetron apparatus in accordance with the present invention, the anode segment may be formed so that the passage of high-frequency current is bent by the first notch and the third notch.
While the novel features of the invention are set forth particularly in the appended claims, the invention, both as to organization and content, will be better understood and appreciated, along with other objects and features thereof, from the following detailed description taken in conjunction with the drawings.